Cenozoic

Mesozoic

Information provided by geoscience team at Ahmadu Bello University, Zaria, Nigeria --see About

Mahmiya Formation

Mahmiya Fm

Period:

Cretaceous

Age Interval:

mid-Santonian – mid-Campanian

Province:
Sudan E

Type Locality and Naming

Atbara Basin, east of Blue Nile Basin, East Sudan

References:

[Fig. 1: Tectonic model of the West and Central African Rift System (WCARS) and the Central African Shear Zone (CASZ). The red arrow and rectangle represent the Shendi-Atbara Basin and study area (Modified after Fairhead, 1988b).]

[Fig. 2: Stratigraphy of the CARS (modified from Schull, 1988; McHargue et al., 1992; Guiraud and Bosworth, 1997; Gani et al., 2009; Wolela, 2009; Dou et al., 2013, 2018, 2023a; Liu and Chen, 2014; Eisawi et al., 2015; Mohammed et al., 2016; Bussert et al., 2018; Yassin et al., 2017; Mohammed Yasin et al., 2019; Gao et al., 2023)]

[Fig. 3. Stratigraphic chart of Shendi-Atbara Basin showing the rock units succession and the basin evolution (from Babkir et al., 2023).]

[Fig. 4. Map showing the location of WCARS basins in between major cratonic areas in Africa, including the subdivision into a Western, Arabian-Nubia, and Southern Austral block (modified from Genik, 1993; Meert and Lieberman, 2008).]

Lithology and Thickness

The formation is dominated by sandstones with a few shale beds (Fig. 9 of Lenhardt et al., 2025)

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

Bagrawiya Fm, conformably

Upper contact

Shendi Fm, conformably

Regional extent

Atbara Basin, Sudan

GeoJSON

{"type":"Feature","geometry":{"type":"MultiPolygon","coordinates":[[[[33.74,17.19],[33.48,16.79],[33.7,16.08],[34.08,16.68],[34.07,17.31],[34.42,17.39],[35.14,16.59],[34.9,16.53],[34.62,16.66],[34.67,15.84],[33.87,15.59],[33.13,16.07],[32.82,16.68],[33.31,17.36],[33.74,17.19]]]]}}

Fossils

Age

mid-Santonian to lower-middle Campanian (strat column of Lenhardt et al., 2025)

Age Span:

Beginning stage:

Santonian

Fraction up in beginning stage:

0.5

Beginning date (Ma):

84.68

Ending stage:

Campanian

Fraction up in the ending stage:

0.4

Ending date (Ma):

79.06

Depositional setting

fluvial setting (Babkir et al., 2023).

Depositional pattern:

Additional Information

Compiler:

Enam O. Obiosio, Solomon Joshua Avong and Henry Nasir Suleiman (2024) - Stratigraphic Lexicon compiled from the following books:

Lenhardt, N., Omietimi, E.J., Edegbai, A.J., Schwark, L., Catuneanu, O., Fairhead, J. D., Gotz, A. E. (2025): Traversing the rift: A review of the evolution of the West and Central African Rift System and its economic potential. Earth-Science Reviews, 261: pp. 1-39

Babkir, M.D.B.H., Nton, M.E., Eisawi, A.A.M. (2023): Depositional environment and hydrocarbon exploration potential based on sedimentary facies and architectural analysis of the Upper Cretaceous Shendi Formation in Musawwarat-Naga area, Shendi-Atbara Basin, Sudan. Earth Sci. Research Jour., 27(2): 109-128